Ceramic-coated mufflers and methods of making same



April 1970 J. c. BLOME 3,507,357

CERAMIC-COATED MUFFLERS AND METHOD OF MAKING SAME Filed May 9, 1968 JAME6 C. BLOME United States Patent 0.

3,507,357 CERAMIC-COATED MUFFLERS AND METHODS OF MAKING SAME James C. Blome, 12330 Winnsboro Drive, Bridgeton, Mo. 63042 Filed May 9, 1968, Ser. No. 727,869 Int. Cl. B21d 51/18; C23d 5/10; F0111 7/18 U.S. Cl. 18161 10 Claims ABSTRACT OF THE DISCLOSURE The present invention relates generally to an improved mufiler and a method for constructing such a muffler and similar devices. The component parts of the muffler are coated with ceramic and then secured to one another using a suitable adhesive so that no break occurs in the ceramic coating.

BACKGROUND OF THE INVENTION Automobile mufllers generally consist of an outer shell or housing, a plurality of chambers and baffies within said shell, and inlet tubes and exhaust tubes. During typical operation rnufllers are subjected to the deteriorating effect of corrosive agents such as internal gases and condensation'in addition to road chemicals, water and abrasion. In order to minimize the harmful effects of these substances which substantially reduce the life of mufilers it has become the practice of some producers in the muffler industry to coat the exposed surfaces with a 10 cost ceramic coating such as porcelain enamel. To achieve satisfactory results it is necessary to cover all exposed surfaces. Principal methods utilized to achieve this coating have been directed towards methods whereby a metallic mufiler is fully assembled by spot-welding or other conventional techniques and then the assembled mufller is dipped in a water suspension of porcelain enamel. A difficulty associated with this approach is the inability thereafter to reliably and economically inspect the interior coating for defects.

Other methods used to achieve this coating generally involve coating the individual parts of the muffler prior to assembly and then assembling the muffier from coated components. However, in this latter approach, the techniques for joining the component parts generally involves a process of spot-welding, brazing or similar technique, and requires the removal of the porcelain enamel at critical points so that a joint may be effected.

Thus with the principal techniques presently in use, there is generally a high probability of an end product with areas which are vulnerable to the aforementioned corrosive forces.

SUMMARY OF THE INVENTION It is accordingly a primary object of the present invention to provide an improved ceramic-coated muffler assembly for the exhaust system of an automotive vehicle.

It is another object of the present invention to provide an improved mufi ler assembly with the service life equal to the full capability of ceramic enameling on steel.

It is another object of the present invention to provide an improved long-life muffler assembly of the above character which may be easily assembled and economically manufactured.

It is another object of the present invention to provide a mufiler constructed in accordance with and embodying the present invention wherein said mufiler is completely coated internally and externally with a ceramic coating.

It is another object of the present invention to provide 3,507,357 Patented Apr. 21, 1970 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal cross sectional view of an assembled mufiler constructed in accordance with and mbodying the present invention.

FIG. 2 is a longitudinal cross sectional view of an end cap assembly used in the construction of the muflier shown in FIG. 1, constructed in accordance with and embodying the present invention.

FIG. 3 is a cross sectional view of an outer shell used in the construction of the muffler shown in FIG. 1, constructed in accordance with and embodying the present invention.

FIG. 4 is a fragmentary cross-sectional view of a shell and end cap assembly joint constructed in accordance with and embodying the present invention.

FIG. 5 is a fragmentary cross-sectional view of a shell and end cap assembly joint constructed in accordance with and embodying the present invention.

FIG. 6 is a fragmentary cross-sectional view of a mufiler constructed in accordance with and embodying the present invention.

DETAILED DESCRIPTION OF INVENTION Referring now in more detail and by reference char acters to the drawings which illustrate practical embodiments of the present invention, FIG. 1 designates a muffler 1, constructed in accordance with and embodying the present invention, shown in cross section.

The muffler 1, comprises an outer shell 2, an end cap assembly 3, and an end cap assembly 4. It is not essential to the present invention that the breakdown of sub-assemblies or the particular configuration be exactly as shown in FIG. 1.

End cap assembly 3, as shown in FIG. 1 and FIG. 2, is provided with an inlet tube 5, upon which are mounted chamber plates 6 and 7. End cap assembly 4, is provided with an outlet tube 10, and chamber plates 8 and 9. These elements, when mounted in shell 2, shown in FIG. 3, in the fully assembled mufller 1, cooperate to provide the desired acoustic effect.

A method of constructing mufilner 1, consists of fabricating the components thereof from conventional metals. The mufller components are each spray coated or dip coated using a porcelain enamelsuspension. After the porcelain enamel coating has dried the components are fired at normal porcelain enamelling temperatures, typically 1400 degrees Fahrenheit for approximately 15 minutes. After the mufiler components have been fired and the coating is thereby fused to the metal, the components are allowed to cool at room temperature. As a result of this approach all components are completely coated With a hardened, corrosive resistant ceramic coating 17, shown in detail in FIGS. 4, 5 and 6. Inspection of the individual components to determine flaws in the coating is easily accomplished at this point in the process.

The method of bonding end cap assemblies 3 and 4, to the outer shell 2, to form the completed mufiler 1, is performed in the following manner. The surfaces to be bonded together are cleaned of dirt and grease preferably with a solution of acetone. A primer appropriate to the adhesive, if required, is then applied to the cleaned surfaces. After the primer has dried an appropriate adhesive is applied to the primed surfaces. End cap assemblies 3 and 4, are then slid into outer shell 2, and mate with each other as shown in FIG. 1 and the adhesive is allowed t cure.

The preferred adhesive to be used in bonding together the components of mufiiler 1, is an elastomeric silicone adhesive which possesses a temperature resitance of approximately 400 degrees Fahrenheit. Desired qualities in the adhesive chosen are high thermal stability or high temperature resistance and flexibility over an operational temperature range which normally extends from outdoor ambient temperature to approximately 600 degrees Fahrenheit on surfaces subject to direct impingement or hot gases.

Suitable commercially available elastomer adhesives fall into the classes of silicones, fluorocarbons, ester imides, nitriles, polysulfides, flexible epoxies, polychloroprenes and urethanes. The temperature resistance of these adhesives ranges from approximately 250 degrees Fahrenheit to approximately 400 degrees Fahrenheit. Suggested for use with silicone and fluorocarbon adhesives is a silane primer while for ester imide an epoxy primer is suggested. For the other elastomeric adhenives listed above, no primer is required except a urethane primer for urethane adhesives.

Another commercial adhesive which is suitable for the practice of the present invention is a brittle high temperature ceramic adhesive, with a temperature resistance of approximately 2000 degrees Fahrenheit, for which no primer is required.

FIGURE 1 illustrates the structural features of the coated and assembled muffler 1, constructed in accordance with and embodying the present invention, wherein the adhesive 11, is shown circumferentially bonding the end cap assemblies 3 and 4, to outer she l 2. As shown in FIG. 1, outer shell 2, is flared outwardly at each end thereof, thereby providing in combination with said end cap assemblies which are fabricated to provide flange 12, an annular space of essentially triangular cross-section for placement of the aforementioned adhesive 11.

FIG. 4 illustrates another structural arrangement of the bonding surfaces of outer shell 2 and end cap assemblies 3 and 4, wherein said end-cap assemblies are fabricated so as to provide a flange 13, oppositely extending to flange 12, shown in FIG. 1, so that the outer diameters of said end-cap assemblies are slightly less than the inner diameter of outer shell 2, thereby providing an annular space of essentially rectangular cross-section for placement of said adhesive 11.

FIGURE 5 is another embodiment of the present invenvention illustrating another structural configuration of the bonding surfaces of outer shell 2, and end cap assemblies 3 and 4, wherein said end cap assemblies are fabricated so as to provide a flange 14, extending in the same direction as flange 12, shown in FIG. 1, so that the inner diameters of said end cap assemblies are slightly greater than the outer diameter of outer shell 2, thereby providing an annular space of essentially rectangular cross-section for placement of said adhesive '11.

In the construction of the bonding portions of the muffler components, it is clear that the constructions shown in FIG. 1 and FIG. 5 are such as to provide a mechanical seat for outer shell 2, when mated with end cap assemblies 3 and 4. It is also clear from FIGS. 1, 4, and 5, that adhesive 11 as shown therein is subject to direct impingement of exhaust gases for the construction shown in FIG. 4, whereas this impingement is indirect for the construction shown in FIGS. 1 and 5.

Exhaust gas temperatures for conventional motor vehicles have been experimentally determined to range from ambient to approximately 440 degrees Fahrenheit. To minimize any degrading effect these hot gases may have on adhesive 11, flange 13, as shown in FIG. 4, is extended sufficiently so as to allow substantial reduction in temperature outwardly along flange 13, resulting in a significant length of flange 13, being at temperatures which minimize degrading of adhesive 11, under operational conditions. Use of a flange 13, approximately 1 inch in length, has been shown to be satisfactory when adhesive 11, is elastomeric silicone adhesive.

FIG. 6 illustrates another embodiment of the present invention wherein the structural configuration shown in FIG. 4, is used with the addition of annular ring 15, which is bonded to end cap assemblies 3 and 4, and has an outer diameter slightly less than the internal diameter of outer shell 2, a suitable annular ring 15, may be constructed from a thermal insulation material such as a hardened or unhardened aluminosilicate fiber composite material. Annular ring 15, is bonded to end cap assemblies 3 and 4, using a high temperature ceramic adhesive 16. Annular ring 15, substantially decreases direct impingement of high temperature gases upon adhesives 11 and 16, thereby minimizing any degrading effect these gases may have on said adhesives. It is also to be noted that adhesive 11, is of a material which is less rigid than the material used for adhesive 16. In typical operation, end cap assemblies 3 and 4, are indirectly, rigidly attached to the frame of the motor vehicle thus vehicle vibrations are transmitted to mufiler 1. Adhesive 11, will provide damping of vehicle vibrations and thus increase the life of the muffier 1.

While I have illustrated and described the preferred embodiments of my invention, it is to be understood that changes and modifications in the form, construction, arrangement and combination of the parts and steps of the mufflers and methods of making and using the same may be substituted for those herein shown and described without departing from the nature and principle of my invention.

Having thus described my invention, what I claim as new, and desire to secure by United States Letter Patent 1. A muflier comprising,

an outer housing, said outer housing having an inlet end and an outlet end,

inlet and outlet end cap assemblies adapted to close the inlet and outlet ends of said outer housing, said outer housing and end cap assemblies having a layer of ceramic material on the surface thereof, and

adhesive means disposed on the mutually adjacent surfaces of said outer housing and end cap assemblies.

2. The mufiler of claim 1 wherein the adhesive means is an elastomeric silicone adhesive.

3. The mufiler of claim 1 wherein theadhesive means is an elastomeric fluorocarbon adhesive.

4. The mufller of claim 1 wherein the adhesive means is an elastomeric flexible epoxy adhesive.

5. The muffler of claim 1 wherein the adhesive means is an elastomeric polysulfide adhesive.

'6. The muflier of claim 1 wherein the adhesive means is an elastomeric urethane adhesive.

7. A mufiler comprising,

an outer housing, said outer housing having an inlet end and an outlet end, inlet and outlet end cap assemblies adapted to close the inlet and outlet ends of said outer housing, said outer housing and end cap assemblies having a layer of ceramic material on the surface thereof, and

adhesive means disposed on the mutually adjacent surfaces of said outer housing and end cap assemblies,

insulating means operably attached to said end cap assemblies, said insulating means disposed so as to inhibit exhaust gases from impinging upon said adhesive means.

8. The method of constructing mufllers, said method comprising,

applying a ceramic coating to the surfaces of the component parts thereof,

applying an adhesive to the mutually adjacent surfaces of said component parts, and curing said adhesive. 9. The method of constructing mufilers, said method comprising,

applying a ceramic coating to the surfaces of the component parts thereof,

applying a primer to the surfaces of said component parts, applying an adhesive to the mutually adjacent surfaces of said component parts, and

curing said adhesive.

10. The method of constructing mufilers, said method comprising,

applying a ceramic coating to the surfaces of the components parts thereof,

applying a cleaner to the surfaces of said parts,

applying a primer to the surfaces of said parts,

applying an adhesive to the mutually adjacent surfaces of said component parts, and curing said adhesive.

References Cited UNITED STATES PATENTS 2,229,526 1/1941 Schabacker. 2,239,509 4/ 1941 Vecker. 2,395,005 2/ 1946 Kuhn. 2,825,421 3/1958 Bryant 181-62 XR 3,209,862 10/1965 Young 181-61 3,220,506 11/1965 Vernet 18161 XR ROBERT S. WARD, JR., Primary Examiner U.S. Cl. X.R. 

